Analysis of the Structure, Thermal, and Molecular Dynamics of Organic-Inorganic Hybrid Crystal at Phases IV, III, II, and I: [NH2(CH3)2]2CdBr4

A comprehensive understanding of the physicochemical properties of organic-inorganic hybrids is essential for their solid-state lighting applications. Therefore, a single crystal of [NH2(CH3)(2)](2)CdBr4 was grown; the crystal structure was monoclinic, and the phase transition temperatures for the four phases IV, III, II, and I were 383 K (T-C1), 417 K (T-C2), and 427 K (TC3). Furthermore, the chemical shifts caused by the local field around H-1, C-13, N-14, and Cd-113 changed continuously with temperature, especially near TC1, indicating that the local environment changes with temperature. Owing to the large change in Cd-113 chemical shifts, the coordination geometry of Br around Cd in the CdBr4 tetrahedra changes near T-C1. Therefore, it is proposed that Br plays a significant role in the N-H center dot center dot center dot Br hydrogen bond. Finally, the spin-lattice relaxation time T-1 rho, representing the energy transfer around the H-1 and C-13 atoms of the cation, changed significantly with temperature. The activation energies obtained from the T-1 rho results were two times larger at high temperatures than at low temperatures. This study provides an understanding of the fundamental properties of organic-inorganic hybrid compounds to broaden their applications.